Final answer:
A lesion in the mouth that heals with a scar could be a canker sore, herpes simplex virus infection, or could be related to a developmental issue like cleft lip. Canker sores are not contagious while cold sores are, and sometimes medical treatment may be necessary.
Step-by-step explanation:
A lesion in the mouth that heals with a scar on a young boy's lip could have several causes. One possibility is a canker sore, which is an ulcer that can appear on the lips or inside the mouth. Canker sores are not contagious and typically heal on their own after a week or two, possibly leaving a scar if they are severe.
Another possibility is herpes simplex virus (commonly known as cold sores), which can cause lesions around the mouth. These are contagious and can recur throughout a person's life. In some cases, if there is a notable scar that's present from infancy, it could be due to cleft lip, a developmental defect that may require surgical intervention. Treatments vary depending on the cause, but may include topical ointments, dietary changes, or medical procedures if necessary.